Project Summmary/Abstract The overall goal of this multi-phase SBIR research e[unreadable]ort is to create a PDA-based instrument for the com- prehensive assessment of chronic pain (i.e., the location, quality, intensity, distress, interference, and beliefs dimensions) that o[unreadable]ers improved accuracy and e[unreadable]ciency over conventional approaches. The KnowPain assess- ment instrument will be able to provide reliable and valid ratings of pain with signi[unreadable]cant reduction in both the required number of questions and assessment time. Existing multidimensional chronic pain assessment protocols often require an hour or more to complete. Item response theory (IRT) and computerized adaptive testing (CAT) are the key technologies that will enable more accurate and e[unreadable]cient administration of pain questionnaires. Multivariate IRT (MIRT) will be used to perform a statistical study of questionnaire item performance as it relates to the underlying respondent traits. All necessary tests of IRT assumptions, item calibrations, assessments of model [unreadable]t, and di[unreadable]erential item functioning will be performed. The MIRT analyses will result in a calibrated bank of pain assessment items that will be utilized by the CAT-driven KnowPain instrument to optimize the e[unreadable]ciency of pain assessment via administration of a minimum number of appropriate items. The KnowPain assessment instrument will be tested with human subjects in a validation trial against conventional measures.